Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!swrinde!elroy.jpl.nasa.gov!decwrl!sgi!shinobu!odin!soul!jeffs
From: jeffs@soul.esd.sgi.com (Jeff Smith)
Newsgroups: comp.unix.aix
Subject: Re: xengine performance on RS6000
Message-ID: <1991Apr18.173712.18925@odin.corp.sgi.com>
Date: 18 Apr 91 17:37:12 GMT
References: <1991Apr17.190136.17974@nrcnet0.nrc.ca> <1991Apr17.202630.28470@eagle.lerc.nasa.gov>
Sender: news@odin.corp.sgi.com (Net News)
Organization: Silicon Graphics, Inc.  Mountain View, CA
Lines: 19

In <1991Apr17.202630.28470@eagle.lerc.nasa.gov> fsfrick@bones.lerc.nasa.gov (David Fricker) writes:

>In a related vein, we've done some 'benchmarking' using local programs
>on an RS6000 model 530 & various SGI Irises.  The relative performance
>figures are _very_ strange.  On one CFD program doing a 2D grid, an
>SGI Personal Iris (4D/25) outperforms my RS6000 model 530, while a 
>3D grid run has my model 530 outperforming a 4D/340VGX Iris! (The 340
>means the iris has 4 processors.)  Both programs were written by the
>same person & solve roughly the same problem--vortex sheet rollup--but
>one program solves it in 2D while the other solves it in 3D.

>Any ideas as to why these relative performance figures are so strange?

The 3d model probably is very floating point intensive, which is where
the RS/6000's really shine.  Does the application on the 4D/340VGX
take advantage of having multiple CPUS?  If not, it will have a
tough time keeping up to the 530.

jeffs@sgi.com